Optimizing Perinatal Outcome in High Risk Pregnancies Using Doppler Velocimetry

Abstract

BACKGROUNDHigh risk pregnancies poses a threat for fetoplacental vascular supply and are a risk for fetal growth retardation. Umbilical artery Doppler velocimetry is an important test among the invasive tests used for evaluating the fetal well-being. This study was taken to detect any abnormalities in fetoplacental unit and fetal circulation in high risk pregnancies, to identify the hypoxemic fetus and time the delivery before the occurrence of academia and to compare the perinatal outcome with doppler indices. STUDY DESIGN AND RESULTSThirty (30) patients with gestational age at or beyond 32 weeks of gestation who belong to high-risk pregnancies were included in the study and were subjected to clinical examination, biochemical tests, ultrasound and colour Doppler study. They were serially followed up with ultrasound and color Doppler at 34 and 36 weeks respectively. Findings of USG and Doppler studies were correlated with the perinatal outcomes. The uterine artery, umbilical artery and the Middle Cerebral Artery (MCA) Doppler indices for the corresponding gestational age were compared with the reference values. The middle cerebral artery Doppler index was considered abnormal, if the value was below the 5th percentile of previously published values for gestational age. A single cut off value (1.08) was used for Cerebroplacental Ratio (MCA PI/UA PI), above which the cerebro-placental ratio was considered normal and below which it was considered abnormal. CONCLUSIONSThe degree of abnormality in Doppler indicates the degree of fetal compromise. Absent End Diastolic Flow (AEDF) represents the extreme form of altered velocity in the umbilical arteries and it represents the fetus at highest risk of hypoxia. Reverse End Diastolic Flow (REDF) is an ominous sign indicating that the vascular resistance has reached a point where the blood flow is reversed during diastole indicating acidotic fetus. The foetuses with abnormal wave forms suffer from chronic hypoxia and are usually growth retarded. They are at increased risk for hypoxia and acidemia. The present study shows that in the high-risk pregnancies, serial Doppler velocimetry helps the obstetrician to identify fetus at hypoxia and timely delivery preventing acidemia.

Role of Colour Doppler in the Prediction of Perinatal Outcome in Intrauterine Growth Restrictions

“…In fact, a series of Doppler ultrasound in IUGR foetuses showed a progressive reduction of MCA PI [12] . Moreover, percutaneous umbilical blood sampling revealed a significant correlation between mild arterial hypoxemia in IUGR foetuses and abnormal MCA PI [10] . Besides, uterine artery (UA) Doppler waveform analysis helps to differentiate between the placental causes of growth restriction from other causes [10] .…”

“…Moreover, percutaneous umbilical blood sampling revealed a significant correlation between mild arterial hypoxemia in IUGR foetuses and abnormal MCA PI [10] . Besides, uterine artery (UA) Doppler waveform analysis helps to differentiate between the placental causes of growth restriction from other causes [10] . A prospective study by Zimmerman et al revealed the importance of UA Doppler for predicting IUGR development [11] .…”

“…In fact, abnormality in Umb A waveform indicates a foetal compromise [8] and subsequently considered to be a marker for uteroplacental insufficiency. Umb A absent end diastolic flow indicates high risk of foetal hypoxia due to altered blood velocity and reverse end diastolic flow represents acidotic foetuses [10] . Prolonged hypoxic stress leads to circulatory adaptation in foetus resulting in redistribution of cardiac output, in order to supply oxygen constantly to the brain and heart [10] .…”

“…Umb A absent end diastolic flow indicates high risk of foetal hypoxia due to altered blood velocity and reverse end diastolic flow represents acidotic foetuses [10] . Prolonged hypoxic stress leads to circulatory adaptation in foetus resulting in redistribution of cardiac output, in order to supply oxygen constantly to the brain and heart [10] . The foetal hypoxia is also associated with increased diastolic flow in middle cerebral artery (MCA), which usually shows low diastolic flow, hence acts as a marker of vasodilation [11] .…”

“…The foetal hypoxia is also associated with increased diastolic flow in middle cerebral artery (MCA), which usually shows low diastolic flow, hence acts as a marker of vasodilation [11] . This increased diastolic flow reduces the MCA pulsatility index (PI) [10] . In fact, a series of Doppler ultrasound in IUGR foetuses showed a progressive reduction of MCA PI [12] .…”